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diy solar

All In One Box and Solar Panel numbers?

John Lyman

New Member
Joined
Aug 22, 2020
Messages
16
I have 2 100 watt panels in parallel going into the 12 volts MPP Solar All In One box then into a 100ah LiFePO4 Battery. I live in Southern California. At the beach, on a clear bright, and sunny day, the box says those panels at 1:00 pm are producing 17v, 5a, and 89w. It is charging the battery but do these numbers sound right? Should they be more? Also at night without any load or anything plugged into the AC, the battery goes from 13.3 volts to 10.9 volts in a matter of a few hours. Any idea what is draining the battery? Thank you for your help, John Lyman
 
Tilt and orientation with respect to South can make a difference. Today was the shortest day of the year and my panels produced half of the kWhs that they produced in summer. It could be your battery is not getting fully charged. 13.3 could be anywhere on the discharge curve which is pretty flat at that voltage. Do you have any way to count the Ahrs going into the battery from your MPP Solar inverter? Do you know what the voltage was when they battery finished charging? Perhaps give the battery a full charge with a wall charger and see if they last through the night. They should be full when at 13.6 or 13.8 and then settle at 13.3 or 13.4 volts. There is some overhead that the inverter will draw.
 
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